Bonded non-woven fibrous products and methods for making them



BONDED NON-WOVEN FIBROUS PRODUCTS AND METHODS FOR MAKING THEM Benjamin B. Kine and Nathaniel A. Matlin, Levittown,

Pa., assignors to Rohm 8.: Haas Company, l-hiiadelphia, Pa., a corporation of Delaware No Drawing. Application August 13, 1956 Serial No. 603,832

15 Claims. (Cl. 154-101) This invention relates to bonded non-woven fibrous or filamentous products having a carded fiber structure or comprising fibrous mats in which the fibers or filaments are distributed haphazardly or in random array. The invention also relates to methods for producing the bonded non-woven fibrous products or shaped articles therefrom. The bonded non-woven fibrous products are useful in the production of articles of either flat or threedimensional shape, including insulating material and the like as will be described more particularly hereinafter.

Hereinafter, the expression random array is intended to include the array of fibers in a carded web wherein partial orientation is frequently present as well as other arrays in which the'fibers are in a completely haphazard distributional relationship.

Heretofore binders of natural rubber latex and aqueous dispersions of synthetic rubbers, such as butadiene copolymer'ized with styrene, acrylonitrile, and so on have been suggested as binders for bonding the fibers in nonwoven fabric structures; but these materials have various disadvantages, among which is the tendency to produce an off-white appearance or cast to the bonded products, and this tendency is so strong it is diflicult to overcome even by the use of optical bleaches or by the use, of white'pigments, such as titanium dioxide. These rubbery binders also produce a rubbery hand which appears to be the result of a complete suppression of the fibrous character insofar as the feel of the product is. concerned. When binders of polyvinyl acetates, chlorides, or their.

copolymers are used, the hand becomes papery, by which ismeant that the product has a crisp, brittle handand conveys the impression of thinness and fragility. It also produces a noise on crumpling that is typical. of papers.

The application of thermoplastic polymers such as simpleesters of acrylic or methacrylic acid produces products in.

aqueous dispersions of rubber, synthetic rubbers, and

acrylic esters, have a strong'tendency to migrate to the surfaces of the fibrous products during drying of' the products to which the dispersions have been applied.

It is an object of the present invention to provide fibrous products made with a binder which can be appliedby way of an aqueous system Without the disadvantages mentioned above that are characteristic of previously applied aqueous binder systems. A further object of the invention is to provide a bonded fibrous product of nonwoven character in which the binder is adapted to beconverted to an infusible and insoluble condition as by heating with or without the presence of'a suitable catalyst as will be pointed out more particularly hereinafter. Itis. a further object of. the present invention to produce,

warm C Patented Apr. 5, 1960 bonded fibrous products of non-woven character from fibers which are incapable of felting, whether of natural or synthetic origin, and especially those which, unlike wool, are of non-proteinaceous character and have relatively smooth surfaces extending longitudinally of the fibers, and because of these surface characteristics are incapable of being converted into a felted product by normal felting operations. A further object of the invention is to provide bonded fibrous products of non-woven character wherein the binder may be substantially uniformly distributed through the body of the structure and has reduced tendency to migrate preferentially to the surfaces of the structure. Other objects and advantages of the invention will be apparent from the description thereof hereinafter.

In a copending application Serial No. 474,264, filed December 9, 1954, in the hands of a common assignee, bonded fibrous products are obtained by treating a fibrous web or mat with an aqueous dispersion of a polyvalent metal compound, yielding polyvalent metal ions, and of a water-insoluble linear copolymer of monoethylenically unsaturated monomeric units comprising 0.5 to 7 mole percent of units containing carboxyl (-COOH) groups, held in stable dispersed condition by means of a non-ionic emulsifier. On drying the treated fibrous product, the copolymer becomes cross-linked to insoluble and infusible condition by the polyvalent metal.

In accordance with the present invention, it has been discovered that solvent-resistant, heat-resistant bonded non-woven fibrous products can be obtained by the application of an aqueous dispersion of a water-insoluble linear copolymer, or salts thereof, of monoethylenically unsaturated monomeric units comprising 0.5 to 10 percent by weight of units containing carboxyl (-COOH) groups Without a polyvalent metal compound provided the fibrous product, after application of the copolymer, is heated to a temperature between C. and 350 C. or even as high as 400 C. for a period of time which may range from as short as a fourth of a minute at the higher temperature and as long as half an hour or more at the lower temperature, either with or without an auxiliary aminoplast of the type described more particularly hereinafter and an acidic catalyst therefor. Generally, baking at the temperatures mentioned increases the solvent resistance and the heat-resistance of the copolymer adequately for many purposes, especially when the copolymer contains at least 2.5% by weight of dicarboxylic acid units, such as those obtained from itaconic acid, or at least 5% by weight of monocarboxylic acid units, such as those obtained from acrylic or methacrylic acid. When less than the minimum proportions of carboxylic acid units just specified are present, it is generally preferred to use an aminoplast along with the copolymer to enhance the resistance of the products to solvents and heat. Some enhancement of these properties is frequently obtained when an aminoplast is used in conjunction with copolymers containing carboxyl units in the higher portion of the broad range specified, but usually the aminoplast is unnecessary in these instances.

The copolymer may be applied in free acid form (-COOH groups) or in the form of an alkali metal salt, such as of sodium, potassium or lithium (e.g. --COONa groups), an ammonium salt (-COONH or a salt of a water-soluble amine, such as methylamine, diethylamine, triethylamine, mono-, di-, or tri-ethanolamine, morpholine, etc. Generally, it is desirable to apply the copolymerdispersion. at a pH at least about 5 and preferably at a 7 pH between 6 and 10.

aqueous copolymer dispersion without encountering stability problems. The versatility of the binder used in the present invention is such as to be readily adapted to various methods of production of the fibrous products.

The bonding of the fibers is effected with a clear, substantially colorless binder which has good adhesion to all sorts of fibers and filaments and even to those of siliceous character including glass which, in the past, have been difiicult to handle because of the difliculty of finding colorless binder materials which are adequately adhesive toward the siliceous material. The binders of the present invention are also substantially free of discoloration when subjected to elevated temperatures, such as those used for drying, fusing, or curing.

The copolymer used in the binder of the present inven tion contains a plurality of carboxyl (COOH) groups either in free acid or salt form by which it is adapted to be insolubilized and rendered infusible on heating with or without an auxiliary aminoplast and suitable catalysts which are generally of acidic character. Hence, the cured or baked fibrous product provides improved resistance to laundering, dry-cleaning and spotting, to various chemicals, and to heat as compared to such aqueous systems as rubber latex or aqueous dispersions of synthetic rubbers or acrylic or vinyl esters, heretofore applied. The bonded fibrous products of the present invention can be heated to a much higher temperature than those of the prior art using the binders mentioned above without suffering discoloration, increase in stiffness 'or deleterious decomposition. They are characterized by excellent resistance to ironing in which operation they are not subject to tackiness as would be true of the thermoplastics heretofore used. The carboxyl groups apparently also provide a greater versatility of adhesion in that the binders of the present invention are characterized not only with good adhesion to hydrophilic fibers like cotton, regenerated cellulose rayons and the like, but they are also characterized by excellent adhesion to hydrophobic types of fibers, such as the nylons and especially the polyamide types, the vinyl resins such as copolymers of vinyl chlo ride with vinyl acetate or with acrylonitrile, polymers of 70 to 90% acrylonitrile with other monomers such as vinyl chloride, vinyl acetate, any of the vinyl pyridines such as 2-vinyl pyridine or mixtures of such auxiliary comonomers, polyesters such as poly(ethylene glycol terephthalate), and cellulose esters such as cellulose acctate, cellulose acetate propionate, cellulose acetate butyrate and so on. Because of the characteristic adhesion of the binder of the present invention to both hydrophilic and hydrophobic types of fibers, the fibrous products are characterized by excellent resistance to pilling and abrasion.

The binder of the present invention is adapted to be dried and then cured to insoluble and infusible condition so that the bonds cannot be disturbed even under severe conditions of heat. The fibrous products using the binder of the present invention have the advantage also that they can be embossed durably in wet condition or during the first drying but before complete drying. This is evidenced by the fact that if the drying is effected on a suction screen through which the excesswater is drained from the fibrous product, the pattern of the screen is permanently imparted to one face of the product and even calendering under normal procedures and temperatures does not destroy this pattern effect. While the binder may be preferentially applied, if desired, to portions of the fibrous product, such as one or both of the faces thereof, it is characteristic of the binder of the present invention that, if such preferential treatment is not desired, substantially uniform distribution may be obtained because of the reduced tendency of the binder after initial distribution throughout the body of the fibrous product to migrate to the surfaces thereof during drying. The binder of the present invention may also contain, besides the linear copolymer, thermosetting aminoplast condensates such as of urea or melamine or the like with formaldehyde and the catalyst used for accelerating the condensation of the aminoplast to insoluble and infusible condition serves simultaneously and/or concurrently for the curing of the carboxylate-containing polymer to the insoluble and in fusible condition.

The cured or insolubilized binders are unaffected by water or organic solvents, such as styrene, even at molding temperatures, whereby the bonded fibrous products are adapted to be used as molding preforms or molding inserts for the production of molded articles from various thermosetting resins as will be pointed out in more detail hereinafter. The binders are also free of cold flow and are resistant to flow at elevated temperatures, whereby shifting of the fibers or filaments in the bonded products is substantially completely prevented even at elevated temperatures during subsequent molding with such products being used as reinforcing inserts or preforms.

In accordance with the invention, a fibrous product, the fibers of which may consist entirely of non-proteinaceous fibers which are incapable of felting, is impregnated with the aqueous dispersion of the water-insoluble linear polymer containing the carboxylic groups. The molecular weight of the polymers should be from about 100,000

to about 10 million.

The aqueous dispersion is preferably obtained by emul sion polymerization in the presence of an emulsifying agent of at least one monomer containing a carboxyl group, such as acrylic acid, methacrylic acid, and itacon' ic acid.

The emulsifiers or dispersing agents that may be used for preparing the monomeric emulsions before copolymerization or dispersions of the polymer after polymer ization may be of anionic or non-ionic type or a mixture of the two types may be used.

Suitable anionic dispersing agents include the higher fatty alcohol sulfates, such as sodium lauryl sulfate, alkylaryl sulfonates, e.g. sodium or potassium isopropylbenzene sulfonatesor isopropyl naphthalene sulfonates, alkali metal higher alkyl sulfo-succinates, e.g. sodium octyl sulfosuccinate, sodium N-methyl-N-palmitoyltaurate, sodium oleyl isothionate, alkali metal salts of alkylarylpolyethoxyethanol sulfates or sulfonates, e.g. sodium t-octylphenoxypolyethoxyethyl sulfate having 1 to 5 oxyethylene units.

Suitable non-ionic dispersing agents include the following: alkylphenoxypolyethoxyethanols having alkyl groups of about seven to eighteen carbon atoms and 6 to 60 or more oxyethylen'e units, such as heptylphenoxypolyethoxyethanols, octylphenoxypolyethoxyethanols, methyloctylphenoxypolyethoxyethanols, nonylphenoxypolyethoxyethanols, dodecylphenoxypolyethoxyethanols, and the like; polyethoxyethanol derivatives of methylene linked alkyl phenols; sulfur-containing agents such as those made by condensing 6 to 60 or more moles of ethylene oxide with nonyl, dodecyl, tetradecyl, t-dodecyl, and the like mercaptans or with alkylthiophenols having alkyl groups ofsix to fifteen carbon atoms; ethylene oxide derivatives of long-chained carboxylic acids, such as lauric, myristic,

palmitic, oleic, and the like or mixtures of acids such as found in tall oil containing 6 to 60 oxyethylene units per molecule; analogous ethylene oxide condensates of longchained; alcohols, such as octyl, decyl, lauryl, or cetyl alcohols, ethylene oxide derivatives of etherified or esterified polyhydroxy compounds having a hydrophobic hydrocarbon chain, such as sorbitan monostearate containing 6 to 60 oxyethylene units, etc.; also ethylene oxide condensates of long-chain or branched chain amines, such as dodecylamine, hexadecylamine, and octadecylamine, containing 6 to 60 oxyethylene groups; block copolymers of ethylene oxide and propylene oxide comprising a hydrophobic propylene oxide section combined with one or more hydrophilic ethylene oxide sections.

woven mat or web in which they are haphazardly distributed. The mat may be formed by carding when the fib s. are a f; uch.-

har et n bua rwe ngth: nd flexibility, as. to be;amenable,;to. the carding operation, Natural fibers like jute, sisal, ramie, h emp,; andcotton maybe used, as well as many; artificial fibers; or filaments including; rayon, those of; celluloseesterssuchyas cellur lose; acetate, vinyl resin. fibers. such as .those :of. polyvinyl chloride, copolymersof vinyl chloride. with vinyl acetate, vinylide'ne chloride. or acrylonitrilecontaining a major proportion of vinyl. chloride. in; the polymer molecule, nolyacrylonitrile and copolymersoflacrylonitrilewith vinyl, chloride, vinyl acetate, methacrylonitrile, vinyl pyridine, or with-mixtures .of such comonomers and cone taining a major proportion from. 75 to 95% of-acrylo nitrile in the copolymer molecule; also condensationpoly mers such. as polyamides of; nylon type, polyesters; such as: ethylene, glycol-terephthalate,v polymers and the like.

The thin web or fleece obtainedfrom a single card may be treated in accordance with thepresentinvention, but generally it is necessary and desirable to superpose a plurality ofsuch webs to build up the mat tosufi icient thickness for the end. useintended,particularly in the making of heat. insulation. In building up. such a mat, alternate layers; of carded webs may, be disposed with their: fiber. orientation directions disposed at 60 or: 90 angles with. respect to intervening layers.

Mats .may also be formed, by the. deposition offibers, either natural or artificial, from an aim stream. Thus, continuous filaments may be fed to. a cutter or breaker which. discharges thefibers, into the discharge sideof. a blower. Suitable. conduits; are provided to; guide the fibers: to.a collecting screenpn air-pervious structure for collecting the. fibers in: the form" desired- The screen may be in the forrnof an endless-traveling belt passin-g. through the lower portion of. a tower into the upper -por; tion of which the blown. fibers;are., introduced: by. the conduit work. A suction box-may. be disposed'beneath thetupper-course of, the, traveling screen to assist in the deposition of the fibers thereon; Instead of; having a traveling flat screen, a, stationary formed screen may. be used. For. example, itmay take the formv of a hat-shaped cone such as that used in the telthat-making industry. Alternatively, it may have anyother. form suitable to produce the desired shape. of the. fibrous product, suchas a rectangular tray. Again, suction may be appliedbeneath the screen to assist deposition of the fibers. thereon.

The fibers. and filaments may be formed by. direct spraying from a solution. or molten, mass thereof. This is. a conventional procedure for the formation of glass fibers ormineral .wool fibers as Well as; those of nylon-or of thermoplastic materials, such as vinyl resins of thetype mentioned hereinabove, adapted to be dissolved in a suitable solvent, such as acetone or. dimethylformamide,. or to. be melted. The solution or melt is, of course, directed' to. suitable nozzles or jet-forming orifices and a highjpressure. fluid stream, such as of cold or hot air or of inert gases such as nitrogen or even of steam, is directed against the streamer streams offilarnent-forming material to disrupt them and coagulate them as fibers in the vicinity of the orifices. Electrostatic spinning methods may also be employed for this purpose. As in the case of the use of blowers, the disrupted and dispersed fibersimay be directed to the top of a settling tower and be allowed to settle, with the aid of suctiondevices, upon a suitable traveling or stationary screen at the bottom of the tower. This procedure is adaptable to'the production of fibersof siliceous material's such-as glass or mineral wool as well as to' thermoplastic resin fibers, mentioned above.

Another procedure may involve the extrusion of continuous filaments, either from solutions of the filamentforming' material or from molten-inassesthereof, and the cutting or breaking of the filaments to fibers of a predetermined length which may be fed to a hopper at; thev top of a settling towerinto; whichthey may be dis-.

charged by conventional, feeding devices, and at the bot-- orn-. t. i h. a av l i t oa ry srscn ay e deposited for collection of thefibers.

The fibersand.filamentsthat maybeused-in the-present invention may benatural or artificialas. stated above. The selection of the particular material-of which the fiber ismadefrequently depends upon -the use intended of the product. For example,siliceous fibers areextremely val: uable in the productionof molded articlesbecauseof the exceptional strengthcbtained by their use. However, when the bonded fibrous p roducts areusedfor filtration purposes, fibers of certain resins may be preferred to provide resistance to attack by acids or alkalies that may be present in the-liquids to be filtered. Thus, poly 'mers containing a high percentage of acrylonitrileor of vinyl chloride-,or even of such highly halogenated resins as polytetrafluoroethylene orpoly(chlorotrifiuoroethylene) may be. more useful in such cases. For certain purposes, it may be desirable toform thefibrous products from a mixturelof fibers of ditterenttypes. An example is the use of a mixtureof thermoplastic fibers of potentially adhesivecharacter with-other fibers which lacksuch potentially adhesivecharacter. A1 fibrous prod; uct'comprising such a mixture may beheated to the ap propriate temperature to render the potentially; adhesive fibers tacky to efiect binding of the fibers in the product by this procedure as well asby the binders of the present invention.

The binder of the present invention is applied in the form of an aqueous dispersion which may be produced by the emulsion polymerization of monomers containing carboxyl groups preferably. with other monoethylenically unsaturated comonomers. Thecomonomersmay bese: lected to providevariousproperties inthebinden Thus, they. may provide a soft and flexible binder or they may provide a hard andstifi binderwhich imparts correspond,- ing stiffness to thebonded fibrousproduct. Surprisingly, dispersions of'copolytners having T valuesof5Q C, and over can be effectively employed to formcoherent-bonded non-woven fabrics, even though thesedispersionsordinarily do not form continuous films when applied totextile fabrics and dried' at temperatures abovettheir'respective T, values.

Useful comonomers which tend to yieldsoftand fiex-. ible polymerswhen copolymerized with one of the .carboXyl monomersv mentioned above: are those; which yield solid polymers which have-a'T, below-15- to 20- C. The T value referred to isv the transition temperature or; inflection temperature which is found by plotting themodulusv of rigidity against'temperature, A convenient: method for determining-modulus of rigidity and transition temperature is described by- I. Williamson, British Plastics 2-3, 87-90, (September 1950). The T value. hereused: is that determined at 300 kg./cm.3.

The polymerizable, neutral, comonomers which. form; soft, solid polymers in the presence of freeiradical catalysts include any. primary and secondary alkyl acrylate, even with alkyl substituents up to eighteen or more carbon atoms, primary or secondary alkyl methacrylates: with alkyl substituents of five to eighteen or more carbon atoms, or other monovinylidene compounds 'as defined above which are polymerizable below C. with free radical catalysts to form soft solid polymers, including vinyl esters of saturated monocarboxylic esters of over two carbon atoms. Thepreferred.monovinylidene compounds. are the stated acrylates and methacrylates and of these the most practical esters are those. with alkyl groups. of not over '12 carbon atoms;

The preferred monomers which by; themselves yield, soft polymers may be summarized by the formula cape-000m R, where Ris hydrogen or the methyl group. and R reprer. sents, when R is methyl, a primary or secondaryalkyl group, of 5, to 18 carbon atoms, or, when R is; hydrogen,

an alkyl group of not over 18 carbon atoms, or better, of two to 12 carbon atoms.

Typical compounds coming within the above definition are methyl acrylate, ethyl acrylate, propyl aerylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, sec butyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, 3,5,5-trimethylhexyl acrylate, decyl acrylate, dodecyl acrylate, cetyl acrylate, octadecyl acrylate, octadecenyl acrylate, n-amyl methacrylate, sec-amyl methacrylate, hexyl methacrylate, 2-ethylbutyl methacrylate, octyl methacrylate, 3,5,5-trimethylhexyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, and bu-' toxyethyl acrylate or methacrylate.

As polymerizable monovinylidene monomers which by themselves form hard polymers, there may be used alkyl methacrylates having alkyl groups of not over four carbon atoms, also tert-amyl methacrylate, tert-butyl or tertamyl acrylate, cyclohexyl or benzyl acrylate or methacrylate, acrylonitrile, or methacrylonitrile, these constituting a preferred group of the compounds forming hard polymers. Styrene, vinyl chloride, chlorostyrene, vinyl acetate, p-methylstyrene, acrylamide, and methacrylamide also form hard polymers.

Preferred monomers which by themselves form hard polymers may be summarized by the formula CHFC-X wherein R is hydrogen or the methyl group and wherein X represents one of the groups CN,, phenyl, methylphenyl, and ester-forming groups, -COOR", wherein R" is cyclohexyl or, when R is hydrogen, a tert-alkyl group 'of four to five carbon atoms, or, when R is methyl, an alkyl group of one to four carbon atoms. Some typical examples of these have already been named. Otherspecific compounds are methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, sec-butyl methacrylate, and tent-' butyl methacrylate.

It is frequently desirable to copolymerize the carboxylcontaining monomer with a mixture of two or more different comonomers, one or more of which are selected from the hard category just mentioned and another of which is selected from the soft category. An example of this would be a copolymer of 8% to 55% ethyl acrylate, 44% to 90% of methyl methacrylate and from about 3% to 6% of methacrylic acid.

The'polymers used as binders of the present invention may also be graft or block copolymers wherein one or more but not all. of the monomers are first polymerized and then one or more other monomers are copolymerized with the first polymer obtained. Thus, a carboxylcontaining monomer may first be homopolymerized or copolymerized with one or more, but less than all, of the comonomers tobe introduced into the ultimate copolymer, and then the last monomer or monomers are added to the system and copolymerized or grafted on to the first homopolymer or copolymer formed. The same procedure may be used in reverse order to graft the carboxyl-containing units on to a previously formed homopolymer or copolymer of other monomeric units. Again, a plurality of'monomeric units may be introduced in succession and the carboxyl=group-containing monomer may be introduced at the beginning, at any intermediate stage' or at the Send, as desired.

For certain purposes, thecopolymer's of the present invention having a T, of-about 30 C. or lower may be preferred. These set onv drying at room temperature to' mat-is desired 'to'be'bent into-the shape of a structureto be covered therewith as in the wrapping of a pipe atcylindrical vessel. Such wrapping can be effected without extensive rupture of the bonds between the fibers and without excessive compacting of the mat, which thereby largely retains its bulky character with numerous small air-spaces and high'heat-insulating value and is subsequently rendered'permanent by the baking operation. However, for certain purposes, it is preferred to use dispersions of copolymers having a T, of 35 C. or higher, such as from 35 to C, In order to effect optimum bonding of the fibers with such a dispersion, it is necessary that the drying be effected at temperatures above the T, temperature of the particular copolymer'. At lower temperatures, the polymer deposits in particu late form in which the particles are of the order of size of the dispersed resin particles in the aqueous dispersion whereby effective bonding is obtained only where the small particles are lodged within close spacings between the intercrossed fibers. The other particles serve to modify the hand of the web or mat but do not contribute appreciably to the cohesion of the web. By driving the treated fibrous product at temperatures above the I, value, fusion or coalescence occurs giving rise to sub stantial masses adequate in size to bind the fibers at their intersections even when the fibers are separated by relatively large spaces as compared to the size of the original polymer particles in the dispersion. The peculiar advantage of the use of dispersions of polymers; having the elevated T, value of at least of about 35 C., is that in the operation of applying the dispersion to the fibrous mass, as by spraying, any excess that is deposited on' the walls of the spraying chamber dries at the prevailing room temperature below 35 C. to discrete particles or a powder which is readily removed from the equipment merely by brushing. To take advantage of this properly, care is taken to avoid any substantial elevation of the temperature in the application equipment, such as the spraying equipment or chamber, a'p preciably above room temperature in cases where the T, value of the copolymeris in the neighborhood of 35 C. Of course, when higher T, values of 55 to 100 C. characterize the polymer, considerable elevation of the temperature in the spraying equipment may be pres ent without encountering coalescence in the excess ma-* terial deposited in the walls of the equipment, provided the temperature surrounding such equipment does not approach too closely (say within 10 C.) the tempera ture of the T, value of the particular polymer involved.

In the preparation of bonded fibrous products of the present invention, which are intended to serve as pre-' forms in the making of molded products, the use of polymers having higher T, values also has the advantage that the preform is much stifier in character and encounters less risk of disturbance of the fibers during the handling of the preform in preparing it for the molding operation per se. I

The dispersions adapted to be used as the binder-applying medium of the present invention are most advantageously prepared by emulsifying with a dispersing agent and polymerizing, preferably under the influence of a free radical catalyst, a'mixture of the monomers of which at least one-half percent is a carboxyl-containing monomer.

Anionic and non-ionic emulsifiers or dispersing agents may-be used. Less advantageously, water-insoluble polymers comprising at least 0.5% of carboxyl-contaim ing monomeric units produced in any other way may be dispersed in water by means of suitable dispersing agents.

The dispersions may contain as little as 1% and as much as 60% of the resinous copolymer on a weight basis. It is, however, more practical-hence preferred-#- to produce disper'sionswhich contain about 30% to 50%" resin-solids. Generally, the dispersion is diluted to 1%- to 35%, and-"preferably 2% to 30%, resin content at 9 which itiis. readilyv adapted: to. be applied. as bwsprayr ing, dipping, or by transferrolls.

The binder dispersion may be applied to the-dry fibers after. the formation or deposition of the web or matso as to penetrate partially into or completely through the interior of the fibrous products. Alternatively, the binder dispersion may be applied to the fibers as they fall through the settling chamber to their point of deposition. This is advantageously obtained by spraying the binder dis.- pcrsion into the settling chamber at some intermediate point between the top and the bottom thereof. By so spraying the fibers as they descend to the point ofcollection it is possible to effect a thorough distributionof the binder among the fibers before they are collected. into theproduct. In the production of certain fibrous. products wherein a hot molten mass ofa polymer, such as nylon or a fused siliceous mass or glass, is disrupted by jets of heated air or steam, the binder dispersion may be sprayed directly on the fiberswhile still. hot and very shortly before their deposition so that'quickly after deposition the binder is set and bonds the fibers in proper relationship. Preferably, however, application of the-binder dispersion to the fibrous product is made at room temperature to facilitate cleaning of the apparatus associated with the applicationof the binder dispersion;

The binder dispersion may be applied to one or both surfaces of the fibrous product or it may be distributed through the interior as well. While the binder. may be applied inpowdered form ineachof the situations just mentioned, in all cases application of the aqueous dis persion is preferred. 1

While chemical reaction probably occurs between the binders of the present invention and fibers, such as those of cellulosic type, which contain reactive groups, it is. not intended that the invention should be limited to this theory operation.

The binder of the present invention may be applied in. conjunction with other binders. For example, another type of binder, such as glue or resin-formingcondensates;

especially aminoplasts such as urea-formaldehyde, melamine-formaldehyde and the like, may be applied either to the interior or to the external surfaces of the fibrous product while the binder. of. the present. invention. is applied to the external surf'acesor. to the interior offlsuch' products. Similarly, the use of potentially adhesive fibers within the fibrous product may also be resorted to in conjunction with the use of a binder of the present invention. The aqueous copolymer dispersion may also contain dissolved therein a water-soluble thermosetting condensation product, especially the aminoplasts, namely the low molecular weight or monomeric reaction products of an aldehyde, and especially formaldehyde with urea, thiourea, biuret, or other homologues' or derivatives thereof, such as N,N-ethyleneurea, N,N'-ethyleneurea, N,N'-dimethylurea, N,N'-diethylurea, N,N'-dimethoxymethylurea, N,N-dimethoxymethylurea, N,N-diethoxy ethylurea, tetramethoxymethylurea, tetraethoxyethylurea. Similar reaction products of formaldehyde with triazines, such as melamine may also be employed, such as N,N-di'- methylmelamine and alcohol-modified-melamine-formaldehyde thermosetting resin condensates, e.g: of methyl and ethyl alcohols, for example, dimethoxymethyl-monomethylolmelamine.

The auxiliary aminoplast binder may be used in an amount up to 25% by weight of the weight ofpolymer' containing carboxyl groups, 2 to 11% being preferably the .nonrwoven fibrous-mat or. web .before onaftenapplica? tion-:of the aqueousdispersion of thepolymer, a catalyst for acceleratingthecuring of the copolymer/aminoplast binder. The catalyst may be used in an amountup'to 2%, preferably about /2 to 1% on the weight of the aminoplast. Thecataly st used-may be selected tea-avoid excessive deterioration. of thefibers used in theparticular fibrous product, butit is in any case an acidic or poten; tially acidic material, the latter. serving as a. latent catalyst and liberating acid on heating. For example, when cellulosic fibers are employed, a latent ammonium salt, such as ammonium chloride or diammoniumzphos: phate. or a latent amine hydrochloride salt, may be employed such as thehydrochloride of triethanolamine, monoethanolamine, diethylamine, and so one If desired, the aqueous dispersion of the polymer cone taining carboxylic units may also contain a wetting-agent to assist penetration of the fibrous web or mat to which. it is applied, and it may contain either a. foaming; agent to provide the binder in a foamed condition inthe final product or it may contain a defoamer when theingrediwents of the aqueous dispersion have a tendency to give rise to foaming, and in a particular case such foaming is undesirable. The-conventional wetting agents, suchv as the sodium salt of dioctylsulfosuccinate may be used and the conventional foaming and defoaming agents may be employed, such as sodium soaps, including sodium oleate for foaming and octyl alcohol or certain silicones for defoaming.

Generally, the proportion of the binder of the present invention to the weight of the fiber component of-the fibrous product may vary widely depending on-the character of the product desired. For the production of preforms, intended to be converted into molded articles, it is preferred to employ from 2 to 10% of the binder of the present invention based on the weight of fibers. In the production of insulation masses, the amount of binder employed may fall in the lower part of the range: just specified if the binderis applied primarily adjacentrto. the surface or surfaces of the product or if it is applied in conjunction with other binders. The aqueous dispersion of the polymer containing the carboxyl groups is generally applied at a concentration of 2 to solids and prefere ably at a concentration of 20 to 40% binder solids by weight.

The fibrous product of non-woven character may con.- tain from 2 to 400% by weight of binderon. the weightof thefibers depending on the purpose for which theproduct is tobe used. When the binder. is to servemainly to bond the-fibers together to form a coherent unitary structure in which the maximum porosity is retained in conjunction with a minimum change of natural fiber hand, there may be. employed from 2 to 50% by weight of binder solids on fiber, the lower proportion of course giving the maximum porosity possible and providing' a minimum change in the natural fiber hand although even with the larger proportion in this range, the porosity is mainly retained and the fiber hand is still evident. The products thus obtained are quite useful for many sanitary uses such as table napkins, bibs, table cloths, sanitary napkin covers, disposable diapers, disposable sheets, and surgical dressings and compresses. It is characteristic of the binder applied in the proportions just stated that there is relatively little or no window paning, that is the interstices between fibers-is left open leaving a highly porous bulky product. Of course, the density of the product can be effected or modified by' the application of pressure to varying extents prior to or, in many cases, even after the curing of the product.

Fibrous products of non-woven character using from 40 to by weight of the binder of the presentinvem tion on the weight of the fiber are generally quite useful.

for garment uses to provide interlining fabrics. for-coats; dresses, and so on, or to provide outer wearing apparel. fabrics, such as blouses, skirts, shirts, etc. The garment! ao'aifi t made of these fabrics need no ironing or pressing to restore their appearance, shape, and hand after hand washing, machine laundering, and drying operation. Besides the general household and apparel uses mentioned above, fibrous products of the invention, in which 2 to 100% by weight of binder on the weight of fiber is employed, find many lightindustrial uses as wiping cloths, lining materials for packaging as filters, and packings and gaskets for industrial machinery.

Fibrous products of the present invention in which -100 to 400% by weight of the binder on the weight of fiber is used are especially useful for heavy industrial uses where durability and resistance ,to wear are desired, such as in industrial gaskets, packings, filters, and so on. The products containing 20 to 200% of the binder of the present invention on the weight of the fiber, are useful as laminating layers, either as interlayers or backing sheets in conjunction with plastic films and sheets as. of polyethylene, nylon, and so on, or in conjunction with textile fabrics of woven, braided, knitted, knotted, or felted character.

It is essential that the drying of the treated fibrous product, that is the fibrous product carrying the binder dispersion, be effected at a temperature above the T of the binder copolymer in order to effect proper coalescence andbonding of the fibers. As pointed out above, if the T,-of'the copolymer is about 30 C. or lower, no special heating is necessary to effect bonding, but it may be advantageous to accelerate the drying of the binder to the set condition. To render the binder infusible, curing at elevated temperatures is effected. Curing temperatures may be as high as 400 C. for setting thebinder, but preferably are in the range from about 110 C. 'to 350 C. The curing serves to render the binder insoluble andin: fusible and, as stated hereinabove, may be assisted by the use of an acidic catalyst Where an aminoplast is used. pointed out hereinbefore, the application of the polymers containing carboxyl groups isadapted to pro vide fibrous products having a wide range of character-' istics. When the binder is present in an amountof about 2 to 50% on the weight of the fibers in the fibrous product, the latter retains a textile hand and can have either a soft or a stiff texture depending on the proportion of carboxyl groups in the polymer and the characteristics of any comonomers used in making it, Using polymers containing to 10% of units containing carboxyl groups in conjunction with such comonomers as result in providing a T value of the copolymer of 20 C. or less and preferably not over 5 C., a soft resilient texture is obtained in conjunction with a textile feel or hand and the cured product is quite resistant to laundering, drycleaning and spotting to various chemicals and heat. In all of the fibrous products previously mentioned, where the binder may be present in the proportion of 2 to 50% as in the products just mentioned or in larger proportions up to 400% on the weight of the fiber, the products are characterized by freedom from discoloration and excellent resistance to laundering, dry-cleaning and spotting, to various chemicals, and heat as in ironing, good adhesion of'the binder to the fibers, and durability of any embossed pattern.

The binder of the present invention is essentially colorless and has the advantage that it undergoes no discoloration at the elevated temperature needed for the drying or bakingof the fibrous products 'or even for the formation of molded articles with the fibrous products of the present invention used as preforms and ultimately occurring as a reinforcing component in the molded article. The binder of the present invention is resistant to flow at elevated temperatures so a thermoplastic or thermosetting resin can be applied and the composite thereby obtained can be molded at elevated temperature without appreciably disturbing the disposition of fibers in the mass. Similarly, the binder is insoluble in water and organic solvents so that the presence of such materials during subsequent treatment as in molding cannot disturb the dispositionof fibers. .Consequently, there is no washing" of fibers in the preform with accompanying tendency to form resin-rich areas and fiber-rich areas in the molded article giving rise to such non-uniformity which tends to cause cracking or crazing in the molded articles and resulting weakness in the reinforced structure.

All of these properties render the binder outstandingly valuable in connection with siliceous fibers, such as those of glass or mineral wool, in the production of preforms adapted to be used for forming molded articles. The siliceous fibers are strongly bonded together by means of the binders of the present invention and especially those having a T; temperature above 35 C. and yet the binder is of such character as not to prevent proper integration of the siliceous fibers within the mass of mold ing resin. In the molded products, the presence of the binder has no adverse effect either on the appearance or the strength of the final articles. While molding resins or resin-forming materials of numerous thermoplasticand thermosetting types may be employed, the use of thermosetting types of polyesters is particularly advantageous. Such a resin-forming material may comprise an unsatu rated polyester (such as a polyester of mixed maleic acid and phthalic acid (in a 50-50 molar ratio) with a glycol, such as propylene glycol) dissolved in styrene or other copolym'erizable monoethylenically unsaturated monomers having solvent properties for the low condensed polyester. Most binders heretofore used in the preforms become discolored during the molding operation and interfere with the penetration of the molding resin, especially when it is of a polyester type, so that the fused resin is poorly bonded to the portions of the fibers coated by the binder which in turn is manifested by a reduced transparency and corresponding lack of continuity and homogeneity. The binder of the present invention is resistant to such discoloration. In addition, it does not interfere with the penetration of the resin-forming mate rial to the fibers of the preform during the molding operation. This provides excellent transparency and a high degree of homogeneity and continuity in the product. Also, the binders of the present invenion having the higher T, values and accompanying higher stiffness assure the maintenance of the distribution of the fibers during the handling of the preform up to the molding operation.

The fibrous products of the present invention are capable of numerous uses, many of which have been mentioned above. Thus, the fibrous mats bonded with the improved binders of the present invention may serve as heat or sound insulation materials, as filters for air systerns or liquid systems, as permeable membranes as in storage batteries or electrolytic condensers, as cushioning or padding materials for upholstering purposes and so forth.

As pointed out hereinabove, fibrous mats or fabrics of siliceous fibers are extremely valuable as reinforcements for molded products using the bonded fibrous mat or fabric as a preform with appropriate molding powders or syrups. For example, the bonded mat or the bonded laminar fabric assembly may be introduced into a closed mold system with an appropriate amount of a thermoset-,

ting resin powder or liquid, such as of resin-forming condensates of urea-formaldehyde, melamine-formaldehyde,

phenol-formaldehyde or polyesters, such as those described in US. Patents 2,255,313 and 2,607,756. From,

Instead of using a thermosetting resin-forming mate-.

rial as the molding resin, there may be used thermoplastic types of resins such as the vinyl or acrylictypes.

For example, polymers and copolymers ofvinyl acetate, vinyl chloride, acrylonitrile, styrene, acrylic.

of resins.

and methacrylic acid esters; e.g. the methyl, ethyl, propyl 13 or bntyl estersthereof, and so on. Advantageouslwa polymer or copolymer may be dissolved in its corresponding monomer or mixture of monomers to provide, a solution that may readily be introduced into the mold.

The following examples are illustrative of the fibrous products and the methods for making them in accordance with the present invention and parts and percentages are by weight. unless otherwise indicated:

Example 1 (a) A 75/25 viscose (3 denier, 1 inch staple)/bleached cotton (middling, inch) carded web weighing about 0.75 ounce/square yard is impregnated with an aqueous dispersion containing per 100 parts:

25.0 parts of the ammonium salt of a 66% ethyl acrylate, 32.7% methyl methacrylate, and 1.3% methacrylic acid emulsion copolymer 2 part of t-octylphenoxypolyethoxyethanol containing about 35 oxyethylene units (emulsifier and dispersing agent) 0.4 part of octylphenoxyethoxysodiumsulfate (wetting agent) 0.1 part silicone antifoam at a wet pick-up of about 600% on the weight of the fibers. The web is dried 1.5 minutes at 225 F., and cured 1.5 minutes at 350 F. The resulting non-woven fabric is about 33/67 fiber/binder. It is highly porous and has a soft and resilient feel.

(b) The procedure of part (a) is repeated with Pyrex glass fibers, except that the carded web weighed /2 ounce per square yard and impregnation with the aqueous dispersion is effected at a wet pick-up of 300%, giving a weight ratio of 53/47 fiber to binder in the final fabric which is extremely porous and soft yet coherent.

Example 2 Example 3 The procedure of Example 1(a) is repeated using a similar aqueous dispersion containing 25.0 parts of. the sodium salt of an emulsion copolymer of 87% of 'ethyl acrylate, 10.5% of methyl methacrylate, and-2.5% of itaconic acid. An exceptionally well-bonded non-woven web is obtained that is highly resistant to solvents and heat.

Example 4 The procedureof Example 1(a) is repeated using, a

similar aqueous dispersion containing 25.0 parts of the sodium salt of an emulsion copolymer of 97.5% of ethyl acrylate and 2.5% of itaconic acid. A coherent web like that of Example 3 but with a softer hand is obtained.

Example 5 A 50/50 white nylon/disperse-dyed bright acetate (both fibers 3 denier, 1.5 inch staple) random web obtained by air-deposition weighing about 1.5 oz./sq.'yd. is impregnated with an aqueous dispersion containing per 100 parts:

27.0-parts of the sodium salt of a copolymer of ethyl acrylate, 89.5% methyl methacrylate, and 0.5% of methacrylic acid 2 parts of t-octylphenoxypolyethoxyethanol containing about 35 oxyethylene units (emulsifier and dispersing agent) 3.0 parts of dimethylol-N,N'-ethyleneurea 0.5 part of ammonium, chloride gesyzas 0.5 .part of octylphenoxyethoxysodiumsulfate- (wetting agent) 0.1 part of silicone antifoam at about 300% wet pick-up. The web is dried 1.5 minutes at 225 F., cured six minutes at 350"F. Resultantnone woven fabric is ca. 55/45 fiber/binder. It is quite porous and'has an essentially textile hand. After washing and drying, no ironing or pressing is needed to restorethe shape, appearance, or handof garments made of the fabric.

Example 6 A 50/50 white viscose/dyed Acrilan (polymer of about to acrylonitrile) (both fibers 3 denier, 1.5 inch staple) random web obtained by air-deposition weighing about 1.75 oZ./sq. yd. is impregnated with an aqueous dispersion containing per parts:

at ca. 300% wet pick-up. Dried 1.5 min. at 225 F.', cured five min. at 350 F. Product: 55/45, fiber/ binder; good coherence, porous, soft, textile hand.

It is to be understood that changes and variations may be made without departing from the spirit. and scope of the invention as defined in the a'ppendedclaims.

1. As an article of manufacture, a'HOH-WOVflT'fibIOUS product in which the fiber's are distributed in random array, the fibers of which are predominantly fibers which are incapable of felting selected from the group consisting of cellulosic fibers, nylon fibers, vinyl resin fibers, poly(ethylene glycol terephthalate) fibers, and mixtures thereof,fibers in the product being bonded together by a binder substantially uniformly distributed through the thickness of the productandcomprising a water-insoluble emulsion copolymer of monoethylenically unsaturated monomeric units comprising 0.5 to 10% by weight of a compound selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and ammonium, amine, and alkali metal'salts thereof with at least one ester of an acid selected from the groupconsisting of acrylic acid and methacrylic acid with an alcohol having 1 to 12 carbon atoms, said copolymer being'cross-linked to an insoluble condition whereby the product is substantially resistant to dry-cleaning, the amount of binder being from 2 to 400% of the weight of fibers in the product, and the molecular weight of the copolymer being at least 100,000. g

2. As an article of manufacture, a non-woven fibrous product in which the fibers are-distributed in random array, the fibers of which comprise a predominant pro portion of cellulosic fibers'whicl'iare incapable of felting, fibers in the product being bonded together by a binder substantially uniformly distributed through the thickness of the product and comprising a water-insoluble emulsion copolymer of 0.5 to 10% by weight of a compound selected from the group consisting of aciylicQmethacrvlic. and itaconic acids, and ammonium, amine, and alkali metal salts thereof with at least one ester'of an acid selected from the group consisting of acrylic acid and methacr'ylic acid with an alcohol having 1 to 12 carbon atoms, said copolymer being cross-linked to an insoluble condition whereby the product is substantially resistant to dry-cleaning, the amount of binder being from 2 to 400% of the weight of fibers in the product, and the.

molecular weight .of the copolymer being at least 100,000,

rams

. 15 As an article of manufacture, a non-woven fibrous product in which the fibers are distributed in random array, the fibers of which are predominantly fibers which are incapable of felting selected from the group consisting of cellulosic fibers, nylon fibers, vinyl resin fibers, poly(ethylene glycol terephthalate) fibers, and mixtures thereof, fibers in the product being bonded together by a binder substantially uniformly distributed through the thickness of the product and comprising the reaction product of (1) an aminoplast selected from the group consisting of condensation products of formaldehyde with urea, N,N-ethyleneurea, and melamine and (2) a waterinsoluble emulsion copolymer of monoethylenically unsaturated monomeric units comprising 05 to by weight of a compound selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and ammonium, amine, and alkali metal salts thereof with at least one ester of an acid selected from the group consisting of acrylic acid and methacrylic acid with an alcohol having 1 to 12 carbon atoms, said product being substantially resistant to laundering and dry-cleaning, the amount of aminoplast being from 2 to 25% by'weight of the copolymer and the amount of binder being from 2 to 400% of the weight of fibers in the product, and the molecular weight of the copolymer being at least 100,000.

4. As an article of manufacture, a non-woven fibrous product in which the fibers are distributed in random array, the fibers of which comprise a proportion of cellulosic fibers, fibers in the product being bonded together by a binder substantially uniformly distributed through the thickness of the product and comprising the heatcured product of (1) an aminoplast selected from the group consisting of condensation products of formaldehyde with urea, N,N-ethyleneurea, and melamine and (2) a water-insoluble emulsion copolymer of 0.5 to 10% by weight of a compound selected from the group consisting of acrylic, methacrylic, and itaconic acids, and ammonium, amine, and alkali metal salts thereof with at least one ester of an acid selected from the group consisting of acrylic acid and methacrylic acid with an alco hol having 1 to 12 carbon atoms, said product being substantially resistant to laundering and dry-cleaning, the amount of aminoplast being from 2 to 25% by weight of the copolymer and the amount of binder being from 2 to 400% by weight of fibers in the product, and the molecular weight of the copolymer being at least 100,000. 7

5. A product as defined in claim 4 in which the copolymer is an alkali metal salt of a copolymer of 0.5 to 10% of acrylic acid with ethyl acrylate and methyl methacrylate.

6. A product as defined in claim 4 in which the copolymer is an ammonium salt of a copolymer of 0.5 to 10% of methacrylic acid with ethyl acrylate and methyl methacrylate.

7. A product as defined in claim 4 in which the copolymer is an ammonium salt of a copolymer of 0.5 to 10% of methacrylic acid with ethyl acrylate and methyl methacrylate and the aminoplast comprises dimethylol- N,N'-ethyleneurea.

8. A product as defined in claim 4 in which the copolymer is an ammonium salt of a copolymer of 0.5 to 10% of methacrylic acid with ethyl acrylate and methyl methacrylate and t e aminoplast comprises a condensation product of melamine and formaldehyde.

9. As an article of manufacture, a non-woven fibrous product in which the fibers are distributed in random array, the fibers of which are predominantly fibers which are incapable of felting selected from the group consisting of cellulosic fibers, nylon fibers, vinyl resin fibers, poly- (ethylene glycol terephthalate) fibers, and mixtures thereof, fibers in the product being bonded together by a binder substantially uniformly distributed through the thickness of the product and comprising a water-insolw ble emulsion copolymer of monoethylenically unsaturated monomeric units comprising 0.5 to 10% by'weight of a 16 compound selected from the group consisting of itaconic acid, and ammonium, amine, and alkali salts thereof with at least one ester of an acid seelcted from the group consisting of acrylic acid and methacrylic acid with an alcohol having 1 to 12 carbon atoms, said copolymer being cross-linked to an insoluble condition whereby the product is substantially resistant to laundering and drycleaning, the amount of binder being from 2 to 400% of the weight of fibers in the product, and the molecular weight of the copolymer being at least 100,000.

10. As an article of manufacture, a non-woven fibrous product in which the fibers are distributed in random array, the fibers of which comprise cellulosic fibers, fibers in the product being bonded together by a binder substantially uniformly distributed through the thickness of the product and comprising a water-insoluble emulsion copolymer, having a molecular weight of at least 100,000, of 0.5 to 10% by weight of a compound selected from the group consisting of itaconic acid, and ammonium, amine, and alkali metal salts thereof with at least one ester of an acid selected from the group consisting of acrylic acid and methacrylic acid with an alcohol having 1 to 12 carbon atoms, said copolymer being cross-linked to an insoluble condition whereby the product is substantially resistant to laundering and dry-cleaning, the amount of binder being from 2 to 400% of the weight of fibers in the product.

11. A product as defined in claim 10 in which the copolymer is an alkali metal salt of a copolymer of 0.5 to 10% of itaconic acid with ethyl acrylate and methyl methacrylate.

12. As an article of manufacture, a non-woven fibrous product in which fibers selected from the group consisting of cellulosic fibers, nylon fibers, vinyl resin fibers, poly- (ethylene glycol terephthalate) fibers, and mixtures thereof are distributed in random array, fibers in the product being bonded together by a binder substantially uniformly distributed through the thickness of the product and comp prising a water-insoluble alkali metal salt of an emulsion copolymer, having a molecular weight of at least 100,000, of 0.5 to 10% of itaconic acid with ethyl acrylate and methyl methacrylate, said product being substantially resistant to laundering and dry-cleaning, the amount of binder being from 2 to 400% of the weight of fibers in the product.

'13. A process of making a non-woven fabric which comprises associating, in random array within a web or mat, a mass of fibers comprising a predominant proportion of fibers which are incapable of felting selected from the group consisting of cellulosic fibers, nylon fibers, vinyl resin fibers, poly(ethylene glycol terephthalate) fibers, and mixtures thereof, bringing into contact with the fibers, substantially uniformly through the fibrous mass, an aqueous dispersion containing 2 to 60% by weight of a water-insoluble emulsion copolymer, having a molecular weight of at least 100,000, of monoethylenically unsaturated monomeric units comprising 0.5 to 10% by weight of a compound selected from the group consisting of acrylic, methacrylic, and itaconic acids, and ammonium, amine, and alkali metal salts thereof with at least one ester of an acid selected from the group consisting of acrylic acid and methacrylic acid with an alcohol having 1 to 12 carbon atoms, and drying the fibrous mass containing from 2 to 400%, based on the weight of fibers, of the copolymer at a temperature above the T of the copolymer to efiect fusion of the copolymer and bonding of the fibers thereby, and heating the dried fibrous product at a temperature of 110 to 350 C. to insolubilize the binder with respect to dry-cleaning solvents.

' aqueous dispersion also contains dissolved therein an 14. A process as defined in claim 13 in which the comprises associating, in random: array within aweb or mat, a mass of fibers comprising a predominant proportion of fibers which are incapable of felting selected from the group consisting of cellulosic fibers, nylon fibers, vinyl resin fibers, poly(ethylene glycol terephthalate) fibers, and mixtures thereof, bringing into contact with the fibers, substantially uniformly through the fibrous mass, an aqueous dispersion containing 2 to 60% by weight of a water-insoluble emulsion copolymer, having a molecular weight of at least 100,000, of monoethyleni cally unsaturated monomeric units comprising 0.5 to 10% by weight of a compound selected from the group consisting of itaconic acid, and ammonium, amine, and

alkali metal salts thereof with at least one ester of an' acid selected from the group consisting of acrylic acid and methacrylic acid with an alcohol having 1 to 12 carbon atoms, and drying the fibrous mass containing from 2 to 400%, based on the Weight of fibers, of the copolymer at a temperature above the T of the copolymer to effect fusion of the copolymer and bonding of the fibers thereby, and heating the dried fibrous product at a temperature of 110 to 350 C. to insolubilize the binder with respect to dry-cleaning solvents and launderlng.

References Cited in the file of this patent UNITED STATES PATENTS Nottebohm Sept. 16, Nottebohm Jan. 11, Drechsel Aug. 1, DAlelio Nov. 28, Allenby et al. Sept. 22, Bortnick Aug. 17, Bortnick Nov. 16, Kine Sept. 27, Nottebohm Oct. 4, Nottebohm Oct. 4, Nottebohm Oct. 4, Craemer et a1 Oct. 4, Carlson Dec. 6, Auten et al. Dec. 13, Bodenschatz et al. Aug. 28, McLaughlin et al. Apr. 30, Sumner et al. Feb. 11,

OTHER REFERENCES Ser. No. 202,136, Nottebohm (A.P.C.), published May published May 

1. AS AN ARTICLE OF MANUFACTURE, A NON-WOVEN FIBROUS PRODUCT IN WHICH THE FIBERS AR DISTRIBUTED IN RANDOM ARRAY, THE FIBERS OF WHICH AR PREDOMINANTLY FIBERS WHICH ARE INCAPABLE OF FELTING SELECTED FROM THE GROUP CONSISTING OF CELLULOSIC FIBERS, NYLON FIBERS, VINYL RESIN FIBERS, POLY(ETHYLENE GLYCOL TEREPHTHALATE) FIBERS, AND MIXTURES THEREOF, FIBERS IN THE PRODUCT BEING BONDED TOGETHER BY A BINDER SUBSTANTIALLY UNIFORMLY DISTRIBUTED THROUGH THE THICKNESS OF THE PRODUCT AND COMPRISING A WATER-INSOLUBLE EMULSION COPOLYMER OF MONOETHYLENICALLY UNSATURATED MONOMERIC UNITS COMPRISING 0.5 TO 10% BY WEIGHT OF A COMPOUND SELECTED FROM THE GROUP CONSISTIANG OF ACRYLIC ACID, METHACRYLIC ACID, ITACONIC ACID, AND AMMONIUM AMINE, AND ALKALI METAL SALTS THEREOF WITH AT LEAST ONE ESTER OF AN ACID SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ACID AND METHACRYLIC ACID WITH AN ALCOHOL HAVING 1 TO 12 CARBON ATOMS, SAID COPOLYMER BEING CROSS-LINKED TO AN INSOLUBLE CONDITION WHEREBY THE PRODUCT IS SUBSTANTIALLY RESISTANT TO DRY-LEANING, THE AMOUNT OF BINDER BEING FROM 2 TO 400% OF WEIGHT OF FIBERS IN THE PRODUCT, AND THE MOLECULAR WEIGHT OF THE COPOLYMER BEING AT LEAST 100,000.
 13. A PROCESS OF MAKING A NON-WOVEN FABRIC WHICH COMPRISES ASSOCIATING, IN RANDOM ARRAY WITHIN A WEB OR MAT, A MASS OF FIBERS COMPRISING A PREDOMINANT PROPORTION OF FIBERS WHICH ARE INCAPABLE OF FELTING SELECTED FROM THE GROUP CONSISTING OF CELLULOSIC FIBERS, NYLON FIBERS, VINYL RESIN FIBERS, POLY(ETHYLENE GLYCOL TEREPHTHALATE) FIBERS, AND MIXTURES THEREOF, BRINGING INTO CONTACT WITH THE FIBERS, SUBSTANTIALLY UNIFORMILY THROUGH THE FIBROUS MASS, AN AQUEOUS DISPERSION CONTAINING 2 TO 60% BY WEIGHT OF A WATER-INSOLUBLE EMULSION COPOLYMER, HAVING A MOLECULAR WEIGHT OF AT LEAST 100,000 OF MONOETHYLENICALLY UNSATUTRATED MONOMERIC UNITS COMPRISING 0.5 TO 10% BY WEIGHT OF COMPOUND SELECTED FROM THE GROUP CONSISTING OF ACRYLIC, METHACRYLIC, AND ITACONIC ACIDS, AND AMMONIUM, AMINE, AND ALKALI METAL SALTS THEREOF WITH AT LEAST ONE ESTER OF AN ACID SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ACID AND METHACRYLIC ACID WITH AN ALCOHOL HAVING 1 TO 12 CARBON ATOMS, AND DRYING THE FIBROUS MASS CONTAINING FROM 2 TO 400%, BASED ON THE WEIGHT OF FIBERS, OF THE COPOLYMER AT A TEMPERATURE ABOVE THE T1 OF THE COPOLYMER TO EFFECT FUSION OF THE COPOLYMER AND BONDING OF THE FIBERS THEREBY, AND HEATING THE DRIED FIBROUS PRODUCT AT A TEMPERATURE OF 110* TO 350* C. TO INSOLUBILIZE THE BINDER WITH RESPECT TO DRY-CLEANING SOLVENTS. 